In Japan, engineers are still trying to reduce the hazards at the damaged nuclear reactor complex. Over the weekend, they made some progress but there were setbacks on Monday.

RENEE MONTAGNE, host:

And now to Japan, where engineers are still struggling to reduce the hazards at the damaged nuclear reactor complex there. U.S. Energy Secretary Steven Chu told Fox News this weekend that he's cautiously hopeful.

Secretary STEVEN CHU (Department of Energy): I think with each passing hour, each passing day, things look more under control. And so, step by step, they're making very good progress.

MONTAGNE: Joining us from Tokyo to talk about that progress, along with some setbacks, is NPR's Richard Harris.

Good morning.

RICHARD HARRIS: Hi, Renee.

MONTAGNE: Let's start with the latest from the crippled nuclear power plant.

HARRIS: There was progress over the weekend, but there have also been a couple of setbacks today. First, the utility pulled back its workers from the plant a few hours ago, after grey smoke started rising up from the top of the number three reactor building. That fire eventually went out, and government officials said radiation levels had not risen, which was good news. But then the officials said there - white steam or smoke was coming from reactor unit number two.

And at this point, we don't know what caused either of these incidents, but I can say that we really haven't had a drama like this at the plant since the middle of last week.

MONTAGNE: Well, you said, though - you began by saying there has been some progress. What would that be?

HARRIS: Well, over the weekend, workers actually did a lot to restore electrical power to the reactors. They need that in order to run the cooling systems and other parts of the plant, finally get everything into a safe mode. And without those cooling systems, what they've been doing is using fire trucks to cool off some of the most critical material - that's pools of used nuclear fuel - by spraying it with strong jets of water. They're pumping sea water to these trucks and then refilling the pools with sort of water jets from fire trucks.

And they can't actually see where the water's going, but they've been measuring temperatures of the buildings and from - and radiation levels around the ground, and they say things seem to be getting a lot better. So that's encouraging.

MONTAGNE: Over the weekend, we heard that Japanese authorities found milk, spinach and other greens contaminated with radiation. How widespread, and what are the consequences of that?

HARRIS: Well, they stopped the milk before it went to market, as well as the spinach - at least the spinach they've identified with the tests. And they've decided not to allow any of this material to be exported out of this region of Japan. But, of course, the findings suggest that there could be other cases that just haven't been found, as yet, of contamination. So the government has broadened its search. They actually did find some other contamination on onions, and - but the radiation, overall, that they have found, it's true it does exceed safety standards, but it is also far below what would cause obvious injury.

These dosages fall into this large gray area where public health officials really have to assume that there could be some very small risk. But if it is, actually, it's way too small for them to measure. So - and one other thing, one small town, about 3,500 people, was also advised not to drink the water there, because it also had above-normal radiation readings. So the authorities said it's OK for bathing and washing up.

MONTAGNE: But generally speaking, as of this morning, what impact has all this had on the people who live in that surrounding area?

HARRIS: Of course, many people have had to leave their homes. That includes everyone within 12 miles of the plant, this evacuation zone. And people another six miles beyond that have had to stay indoors. And there's been a - there -most of the radiation that has been spread through this area came, apparently, from one big outburst on March 15th. Radiation levels jumped pretty substantially at that point, although they're still well within the point where scientists can, you know, can't(ph) actually measure an increase of the risk. And the levels have been falling steadily over the past couple of days. So that's encouraging.

MONTAGNE: We just have a few seconds, here, Richard. But talk to us about the workers who were evacuated a little while ago because smoke had been coming from a reactor unit there, reactor number three.

HARRIS: Right. And the workers have gotten a larger dose of radiation than the public, here, but so far, nobody apparently has had a dose that's really lethal, or anything close to that.

MONTAGNE: Well, that's some good news. Thank you very much.

HARRIS: OK.

MONTAGNE: We've been talking with NPR science correspondent Richard Harris. He's speaking to us from Tokyo.

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